HDFS NameNodes

Metrics to see status for the NameNodes.

Table 1. HDFS NameNodes metrics descriptions
Row	Metrics	Description
RPC CLIENT QUEUE TIME	RPC Client Port Queue Time	Average time that a RPC request (on the RPC port facing to the HDFS clients) waits in the queue.
RPC CLIENT QUEUE TIME	RPC Client Port Queue Num Ops	Total number of RPC requests in the client port queue.
RPC CLIENT PORT PROCESSING TIME	RPC Client Port Processing Time	Average RPC request processing time in milliseconds, on the client port.
RPC CLIENT PORT PROCESSING TIME	RPC Client Port Processing Num Ops	Total number of RPC active requests through the client port.
GC COUNT & GC TIME	GC Count	Shows the JVM garbage collection rate on the NameNode.
GC COUNT & GC TIME	GC Time	Shows the garbage collection time in milliseconds.
GC PAR NEW	GC Count Par New	The number of times young generation garbage collection happened.
GC PAR NEW	GC Time Par New	Indicates the duration of young generation garbage collection.
GC EXTRA SLEEP & WARNING THRESHOLD EXCEEDED	GC Extra Sleep Time	Indicates total garbage collection extra sleep time.
GC EXTRA SLEEP & WARNING THRESHOLD EXCEEDED	GC Warning Threshold Exceeded Count	Indicates number of times that the garbage collection warning threshold is exceeded.
RPC CLIENT PORT QUEUE & BACKOFF	RPC Client Port Queue Length	Indicates the current length of the RPC call queue.
RPC CLIENT PORT QUEUE & BACKOFF	RPC Client Port Backoff	Indicates number of client backoff requests.
RPC SERVICE PORT QUEUE & NUM OPS	RPC Service Port Queue Time	Average time a RPC request waiting in the queue, in milliseconds. These requests are on the RPC port facing to the HDFS services, including DataNodes and the other NameNode.
RPC SERVICE PORT QUEUE & NUM OPS	RPC Service Port Queue Num Ops	Total number of RPC requests waiting in the queue. These requests are on the RPC port facing to the HDFS services, including DataNodes and the other NameNode.
RPC SERVICE PORT PROCESSING TIME & NUM OPS	RPC Service Port Processing Time	Average RPC request processing time in milliseconds, for the service port.
RPC SERVICE PORT PROCESSING TIME & NUM OPS	RPC Service Port Processing Num Ops	Number of RPC requests processed for the service port.
RPC SERVICE PORT CALL QUEUE LENGTH & SLOW CALLS	RPC Service Port Call Queue Length	The current length of the RPC call queue.
RPC SERVICE PORT CALL QUEUE LENGTH & SLOW CALLS	RPC Service Port Slow Calls	The number of slow RPC requests, for the service port.
TRANSACTIONS SINCE LAST EDIT & CHECKPOINT	Transactions Since Last Edit Roll	Total number of transactions since the last editlog segment.
TRANSACTIONS SINCE LAST EDIT & CHECKPOINT	Transactions Since Last Checkpoint	Total number of transactions since the last editlog segment checkpoint.
LOCK QUEUE LENGTH & EXPIRED HEARTBEATS	Lock Queue Length	Shows the length of the wait Queue for the FSNameSystemLock.
LOCK QUEUE LENGTH & EXPIRED HEARTBEATS	Expired Heartbeats	Indicates the number of times expired heartbeats are detected on NameNode.
THREADS BLOCKED / WAITING	Threads Blocked	Indicates the number of threads in a BLOCKED state, which means they are waiting for a lock.
THREADS BLOCKED / WAITING	Threads Waiting	Indicates the number of threads in a WAITING state, which means they are waiting for another thread to perform an action.